How will WSDOT know if the viaduct begins to settle during tunneling?

Removing vehicles from the viaduct will allow for easier access to the structure, so crews can better monitor for any structural movement that might occur. The viaduct is monitored in real time by automated sensors and WSDOT will be conducting manual surveys of the structure twice a day. WSDOT bridge inspectors will also conduct pre-tunneling and post-tunneling inspections of the viaduct before reopening the structure to traffic.